Attachment for test indicators



` May 13, `1941.

J. G. sxssoN ATTACHMENT FOR TEST INDICATOS 'Filed July 6.11940 :inventor EMW ..1 .a

- (Ittomegs- Patented May 13, 1941 UNITED STATES PATENT OFFICE ATTACHMENT FOR TEST INDICATORS James G. Ssson, Athol, Mass., assigner to The L. IS. Starrett Company, Athol, Mass., a corporation of Massachusetts Application July 6, 1940, ISerial No. 344,294

Claims. (Cl. 33-172l My present invention provides for an improved attachment for test indicators and particularly for those of dial type having a spring impelled spindle.

In previous attachments of this type the work contacting feeler could only function from one side which prevented the otherwise logical test of the opposite side of the hole or other work surfaces that need to be checked.

As illustrative of my invention I show in the accompanying drawing a simple form well adapted to standard usage.

In the drawing:

Fig. 1 illustrates my attachment as applied to a dial indicator of usual type mounted on a supporting post.

Fig. 2 shows the attachment in side elevation as applied to an indicator stem.

Fig, 3 `is a similar view with indicator case omitted and with the. contact arm held in reversed position. l

Fig. 4 is a section on line 4 4, of Fig, 2, showing the arm pivots,and

. Fig. 5 is a section on the line 5-5 of Fig. 2, but with the lever held reversed as in Fig. 3.

Referring to these illustrative drawings as -a basis of description and discussion, I have indicated at I a typical dial indicator having a stem i and a diametrically reciprocable spindle S. These indicators are of the type wherein the spindle is normally yieldingly thrust diametrically out of the casing by a spring, (not shown) and its inward movements made to register by a pointer on either the plus or the minus side of a zero on the dial scale.

Such indicators are supported in any convenient way as by a horizontal arm extending from the back of the casing and adapted to be clamped in a snug -adjustably mounted on a tool post or like support.

The attachment preferably comprises a bracket I having at one end a clamp 2 tightened by a knurled head screw 3. At its opposite end these brackets usually are provided with a quarter .turn drop 4 having lat its end bearings 5 in which are opposed fulcrum screws 6 engaging with their points bearings in the sides of the arm 1.

At its contact end 8 the arm is formed with a spherical tip 9 while at i-ts opposite end I0 it carries a hemispherical contact II for the end of a spindle as S.

Adjacent the clamp 2 on the lower side of the bracket I I mount my spindle locking member, shown as an arm catch which forms the real element of novelty in the combination. This catch in the form shown may consist of a cylindrical shell `I 2 having on one side a depending hook I3.

At its upper end the shell I2 is slightly flangedinternally as at I4A to aiiord a shoulder for one end of the compression spring I5 which surrounds an axial assembly screw I6. This screw is threaded as at I 6 at one end to engage threads tapped in'the lower face of the bracket I. At its outer end it is headed as at |62 to back up the outer end of the spring I5 and hold it under a slight compression.

When working from the side X of the spherical contact 9, the arm simply fulcrums on its central pivots 6 to push upwardly on the endof spindle S. When it is desired to engage the opposite side of a hole as from Y, the arm 'I is rocked up-V ward and the hook I3 of the rotatable sleeve I2 engaged with the portion I0 adjacent the end contact II which thereby raises and locks the spindle 'against` its usual internal spring resistance. This throws the indicator action into what may be called a reverse position in which pressure from the side Y ofthe spherical end 9 acts to rock the arm 'I, downward against the action of the spring I5 of the arm catch. I2, which spring is of greater power than the return spring for the spindle. By this simple attachment I am able to doub-le the range of potential usefulness of the indicator without changing its mounting or set up relative to work.

My arm locks may be variously designedior various kinds of arm engagement, that shown being of great simplicity of structure and ei` ciency of operation. y

' It may also be variously mounted but for fthe usual type of bracket such vas I, its location closely adjacent the clamp 2 gives it an o-perative position in the axis of the clamp so that it can yieldingly lock the spindle contact end II axially against the actionjof .the spindle spring as previously described. y

What I therefore claim and desire to secure by Letters Patentis:

1. In an attachment for test indicators, a bracket -for clamping to the spindle bearing,l a work contacting lever, means pivoting said lever between its ends in said bracket with one end disposed under the spindle end and a rotatable shell having a depending hook disposed to embrace an adjacent portion of the lever, an axial retaining stud supporting the rotatable shell on said bracket, and a compression spring between the stud and shell andr axially effective to hold said shell yieldingly to said bracket against normal spindle projective action. r

2. An attachment for use with a test indicator'r having a casing, an indicator hand, and a reciprocable spindle, the inward and outward movement'of said spindle determining the direction,l

of movement of the indicator hand and said spindle being normally yieldingly thrust outward,

said attachment comprising a support carried by the indicator casing, a lever pivotally mounted in said support and having a work contacting portion and a portion engageable with the spindle to raise the same and move the hand in one direction when one side of the contact portion enmove downwardly and move the hand in the opposite direction.

3. The attachment of claim 2, the means for yieldingly locking the spindle in elevated position being a manually adjustable spring controlled hook carried by said support and adapted to embrace and elevate an adjacent portion of the lever.

4. The attachment of claim 2, the means for yieldingly locking the spindle in elevated position being a stud mounted in said support, a shell slidable and rotatable over said stud, said shell having lever engaging means, and a spring normally holding said shell in elevated position.

5. An attachment for a test indicator having a spindle bearing, a spindle reciprocable in said bearing, and a spring normally projecting the spindle yieldingly outwardly of said bearing, said attachment comprising a bracket clamped to the test indicator, a lever having a work contacting end and a spindle contacting end, means pivoting said lever between its ends to said bracket with its spindle contacting end in position to thrust the spindle upwardly and inwardly against the action of the spindle spring when contact forces are applied in a downward direction to the work contacting end of the lever, and a lever locking device including a guide portion ilXed to said bracket, a control spring of greater power than the spindle spring, and a lever locking portion axially slidable over said guide portion against the action of said control spring and normally positioned out of locking relation to said lever but manually adjustable into locking engagement therewith and effective when locked thereto to yieldingly hold the spindle at substantially the limit of its inward stroke against the action of the spindle spring so that contact forces thereafter applied in an upward direction to the work contacting end of the lever will move the spindle contacting end of the lever downwardly and outwardly against the action of said control spring to thereby permit the spindle spring to thrust said spindle downwardly and outwardly.

6. The structure of claim 5, the guide portion of the lever-locking device being a fixed stud depending frorn said bracket, the lever-locking portion being a hook-formed shell rotatably and aX- ially slidable on said stud, and the control spring being confined between said stud and shell and compressed by the downward axial movement of said shell over said stud.

7. An attachment for a test indicator having an indicator hand, a spindle bearing, a spindle reciprocable in said bearing, and a spring normally projecting the spindle yieldingly outwardly of said bearing, said attachment comprising a bracket clamped to the test indicator, a lever pivoted between its ends to said bracket with one end disposed for contact with work to be gauged.

and its other end disposed for engagement with the spindle so that when contact forces are applied in a downward direction on said work contacting end the spindle will be thrust by said spindle contacting end upwardly and inwardly against the action of the spindle spring and will drive the indicator hand in one direction, and

means for reversing the direction oftravel of thet indicator hand comprising a yieldable lever lock-f ing device including a guide portion fixed to said bracket, a control spring of greater power than the spindle spring, and a lever locking portion axially slidable over said guide portion against the action of said control spring and normally positioned out of locking relation to said lever but manually adjustable into locking engagement therewith and effective when locked thereto to yieldingly hold the spindle at substantially the limit of its inwardv stroke against the action of the spindle spring so that contact forces thereafter applied in an upward direction `to the workcontacting end of said lever will move said locking device and with it the spindle contacting end of the lever downwardly and outwardly to permit the spindle spring to thrust said spindle downwardly and outwardly and thereby drive the indicator hand in reverse direction.

8. An attachment for reversing the direction of rotation of ythe indicator handvof a test indicator which is normally rotated in one direction by gauging contacts applied in one direction to one end of a pivoted lever and transmitted by the other end of said lever to the indicator hand through a spring-controlled driving spindle, said attachment comprising a yieldable lever locking device having .a spring of greater power than the spindle spring and having a lever-locking portion normally positioned out of locking relation to said lever but manually adjustable into locking engagement therewith and effective when locked thereto to yieldingly hold the spindle at substantially the limit of its stroke in one direction 1 against the action of` the spindle spring so that gauging contacts thereafter applied in the opposite direction to the gauging end of said lever will permit the spindle to rotate the indicator hand in said reverse direction.

9. An lattachment for a gauge having a casing, a spindle reciprocably mounted in said casing, and a spring for normally projecting the spindle yieldingly outwardly of the casing, said attachmen-t comprising a lever which when actuated in a downward direction will thrust the spindle upwardly and inwardly against the action of the spindle spring, and means for reversing the action of said spindle comprising a yieldable locking-device including a fixed guide, a lever-locking portion axially slidable over said guide and rotatably adjustable thereon, and a spring of greater power than the spindle spring opposing the axial sliding movement of said lever-locking portion in one direction, said locking portion being normally disposed out-of-locking relation to said lever but manually adjustable into locking engagement therewith and effective when locked thereto to yieldingly hold the spindle at substantially thelimit of its inward stroke against the action of the spindle spring so that contact forces thereafter applied in an upward direction to said lever will permit the spindle spring to thrust the spindle downwardly and outwardly.

10. A releasable' locking device for the spindle' actuating lever of a test indicator, comprising a xed guide carried by the `test indicator, a shell ial sliding movement of said shell in one direction.

JAMIES G.' SISSON. 

